Manipulator

ABSTRACT

A manipulator, such as for use in medical procedures, is provided. The manipulator includes a body and a first actuator system connected to the body at a first attachment point and capable of moving the first attachment point with at least three degrees of freedom. A second actuator system is connected to the body at a second attachment point and capable of moving the second attachment point with at least three degrees of freedom. A third actuator system is integrated with the body and is capable of moving at least a portion of the body with at least one degree of freedom.

BACKGROUND OF THE INVENTION

Conventional devices which are used to perform very complex and/orphysically demanding surgical procedures like neurosurgery, spinesurgery, ear surgery, head and neck surgery, hand surgery and minimallyinvasive surgical procedures have a number of drawbacks as it relates tothe dexterity of the surgeon. For example, the surgeon can easily becomefatigued by the need to manually support the surgical device during itsuse. Additionally, the surgeon may have to orient his hands in anawkward position in order to operate the device. Furthermore,conventional devices used in such surgical procedures can produceangular magnification of errors. As a result, a surgeon has considerablyless dexterity and precision when performing an operation with suchsurgical devices than when performing an operation by traditionaltechniques in which the surgeon grasps a tool directly.

Accordingly, there is an increasing interest in the use of poweredmanipulators, such as robotic and master-slave manipulators forsupporting and manipulating surgical tools during medical procedures.Such manipulators can provide a number of advantages to both patientsand medical practitioners. In particular, a master/slave controlledmanipulator can enhance the dexterity of the surgeon/operator so as toallow the surgeon to manipulate a medical tool with greater dexteritythan he could if he was actually holding the tool in his hands. Amanipulator can also reduce the fatigue experienced by a surgeon, sinceit eliminates the need for the surgeon to physically support the medicaltool or device during its use. Additionally, the surgeon can let go ofthe manipulator and perform other tasks without the medical toolundergoing movement, which increases the efficiency of the surgeon andcan reduce the number of individuals that are necessary to perform aparticular procedure. Thus, manipulators can allow medical procedures tobe performed much more rapidly, resulting in less stress on the patient.

However, many manipulators, including those having six degrees offreedom, have some drawbacks in that, in certain orientations, theamount of torque that the manipulator can apply is limited. Thisrestricts the work that can be done by the manipulator in suchorientations. Moreover, some manipulators have singularity points withintheir operational envelopes. At these singularity points, two or moremanipulator joints become redundant and fewer degrees of the freedom canbe exercised. This can cause a manipulator mechanism to become locked orimpeded such that it can no longer move freely.

BRIEF SUMMARY OF THE INVENTION

The invention provides a manipulator that includes a body and a firstactuator system connected to the body at a first attachment point andcapable of moving the first attachment point with at least three degreesof freedom. A second actuator system is connected to the body at asecond attachment point and capable of moving the second attachmentpoint with at least three degrees of freedom. A third actuator system isintegrated with the body and is capable of moving at least a portion ofthe body with at least one degree of freedom.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic view of an exemplary manipulator constructed inaccordance with the present invention that includes two three degree offreedom linear axis serial actuators.

FIG. 2 is a schematic view of an alternative embodiment of a manipulatoraccording to the present invention that includes two three degree offreedom rotary axis serial actuators.

FIG. 3 is a schematic view of another alternative embodiment of amanipulator according to the present invention that includes two threedegree of freedom linear axis parallel actuators.

FIG. 4 is a schematic view of a further alternative embodiment of amanipulator according to the present invention that includes a threedegree of freedom linear axis parallel actuator and a three degree offreedom linear axis serial actuator.

FIG. 5 is a schematic view of an alternative embodiment of a manipulatoraccording to the present invention that includes a three degree offreedom rotary axis serial actuator and a three degree of freedom rotaryaxis parallel actuator.

FIG. 6 is a schematic view of a further alternative embodiment of amanipulator according to the present invention that includes a threedegree of freedom mixed architecture serial actuator and a three degreeof freedom mixed architecture parallel actuator.

FIG. 7 is a schematic view of another embodiment of a manipulatoraccording to the present invention.

FIG. 8 is a perspective view of an illustrative manipulator having theconfiguration shown schematically in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

Referring now more particularly to FIG. 1 of the drawings, there isshown an illustrative embodiment of a manipulator constructed inaccordance with the present invention. The illustrated manipulator 10can interchangeably support and move a body with six degrees of freedom.In this case, the moving body can comprise a support member 12 thatcarries an end effector, e.g. a medical tool holder or mount 14. As willbe appreciated, the invention is not limited to any particular type orform of moving body. In this regard, the invention is also not limitedto any particular type of medical tool, tool holder or support structurerather any suitable tool and/or tool support can be used with themanipulator including, but not limited to, needle holders, staple orclamp appliers, probes, scissors, forceps, cautery, suction cutters,dissectors, drills, saws, lasers, ultrasonic devices and diagnosticdevices. The tools can be reusable, limited reuse or disposable. If themedical tool has moving parts that are conventionally human powered, themanipulator 10 can be adapted to accommodate an actuator dedicated topowering the tool such as for example an electric, pneumatic orhydraulic actuator.

While the present invention is described in connection with performingcomplex medical procedures, the manipulator of the present invention isnot limited to such applications. Rather, the manipulator of the presentinvention can be used in any application involving dexterous tasks. Forexample, it can be used in applications involving the remotemanipulation of hazardous materials. It can also be used in complexassembly or repair operations to perform autonomous, but repetitive,tasks normally dome by humans.

In order to provide dexterity enhancement for an operator/surgeon inperforming surgical and certain interventional radiology procedures, themanipulator 10 can be used as a slave robot in a master-slave roboticsystem. The manipulator 10 can also be used as a master robot in such asystem. In a master-slave robotic system, a surgeon/operator providesposition input signals to the “slave” manipulator via a master or hapticinterface which operates through a controller or control console.Specifically, with the manipulator 10 of the present invention servingas the slave robot, the surgeon indicates the desired movement of thetool held by the manipulator 10 through the use of an input device onthe haptic interface such as a six degree of freedom tool handle with orwithout force feedback, joystick, foot pedal or the like. The hapticinterface relays these signals to the controller, which, in turn,applies various desired predetermined adjustments to the signals priorto relaying them to the slave manipulator. Any haptic interface havingan six or more degrees of freedom (DOF) can be used to control themanipulator 10 via the controller. Examples of haptic interfaces ormasters which can be used with the present invention include the Freedom6S available from MPB Techologies of Montreal, Canada, and other hapticinterfaces commercially available from Sensable Technology of Cambridge,Mass. and MicroDexterity Systems of Albuquerque, N. Mex.

Based on the signals provided by the controller, the manipulator 10executes the desired movement or operation of the tool. Thus, anydesired dexterity enhancement can be achieved by setting up thecontroller to perform the appropriate adjustments to the signals sentfrom the haptic interface. For example, this can be accomplished byproviding the controller with software which performs a desireddexterity enhancement algorithm. Software dexterity enhancementalgorithms can include position scaling (typically downscaling), forcescaling (up-scaling for bone and cartilage, downscaling for softtissue), tremor filtering, gravity compensation, programmable positionboundaries, motion compensation for tissue that is moving, velocitylimits (e.g., preventing rapid movement into brain, nerve or spinal cordtissue after drilling through bone), and, as discussed in greater detailbelow, image referencing. These and other examples of possiblealgorithms are well known in the field of robotics and described indetail in published literature. The ZMP SynqNet® Series MotionControllers which employ the SynqNet system and are available fromMotion Engineering of Santa Barbara, Calif. are one example of asuitable controller for use with the present invention (seewww.synqnet.org and www.motioneng.com). Another example of a suitablecontroller is the Turbo PMAC available from Delta Tau Data Systems ofNorthridge, Calif.

To effect movement of the support member 12 in space, the manipulator 10includes first and second actuator systems 16, 18 each of which connectsto the support member 12 at a respective attachment point. Each actuatorsystem 16, 18 comprises a separate, independent three degree of freedommanipulator. The first and second actuator systems 16, 18 can be anytype of three degree of freedom actuator system. More specifically, anycombination of three rotary or three linear actuators can be used toform each of the actuator systems 16, 18. For instance, as shown in FIG.1, the first and second actuator systems 16, 18 could comprise simplelinear axis serial actuators.

In the FIG. 1 embodiment, each of the first and second actuator systems16, 18 comprises three linear sliding joints or actuators 20, 21, 22.Each of the sliding joints/actuators 20, 21, 22 translates or slidesalong a respective Cartesian coordinate axis, i.e. x, y or z. In thiscase, each of the actuator systems includes an x-axis linearjoint/actuator 20 that has one end connected to a solid mount 24 and asecond end connected to a y-axis linear joint/actuator 21. The oppositeend of the y-axis linear joint/actuator 21 is, in turn, connected to az-axis linear joint/actuator 22. The z-axis linear joint/actuator 22 ofeach of the first and second actuator systems 16, 18 connects at arespective attachment point to the support member 12. A “seventh” degreeof freedom is provided by a rotary joint/actuator 28 that is integratedwith the support member 12 and is capable of producing rotary movementof the tool mount 14 relative to the support member 12. The rotaryjoint/actuator 28 integrated with the support member 12 makes up for adegree of freedom from the first and second actuator systems that is“lost” because of the fixed length of the support member 12.

In the embodiment illustrated in FIG. 1, the attachment points of thefirst and second actuator systems each comprise a joint 26, 27, such asa spherical joint, having three rotary degrees of freedom. However, asdiscussed below in connection with the embodiment of FIGS. 7 and 8,according to one preferred arrangement, the attachment point for one ofthe actuator systems can comprise a joint (e.g., a gimbals joint) thathas only two rotary degrees of freedom while the other attachment pointcomprises a joint (e.g., a spherical joint) having three rotary degreesof freedom. Such an arrangement eliminates the free rotation of thesupport member that can occur if two three degree of freedom sphericaljoints are used. While movement of the first and second actuator systems16, 18 can cause some rotation of the support member 12 even with suchan arrangement, the rotation is predictable and can be addressed withcorresponding movements of the first and second actuator systems and therotary joint/actuator 28. The joints can have any desired constructionthat provides the necessary degrees of rotary freedom. Moreover, singlejoints at the attachment points can be replaced with multiple jointsthat collectively provide equivalent degrees of freedom.

An alternative embodiment in which three rotary joint/actuators 130,131, 132 are employed in the first and second actuator systems 116, 118as opposed to linear joints/actuators is shown in FIG. 2. In theembodiment of FIG. 2, elements similar to those found in the FIG. 1embodiment are given corresponding reference numbers in the 100s. As thecase with the FIG. 1 embodiment, the rotary joint/actuators 130, 131,132 are in a serial arrangement with each rotary joint/actuator rotatingabout a respective Cartesian coordinate axis, i.e. x, y or z. In thearrangement illustrated in FIG. 2, each of the first and second actuatorsystems 116, 118 includes an z-axis rotary joint/actuator 132 that isconnected to a solid mount 124. The output shaft of the z-axis rotaryjoint/actuator 132 is connected to a first link 134 that extends to ay-axis rotary joint/actuator 131. The output shaft of the y-axis rotaryjoint/actuator 131, in turn, connects via a second link 135 to a x-axisrotary joint/actuator 130, which has an output shaft that connects to athird link 136 that connects at a respective attachment point to thesupport member 112. With each actuator systems 116, 118, the angles ofthe three rotary joints/actuators 130, 131, 132 define the positions ofthe two attachment points. In this instance, both attachment pointscomprise three degree of rotary freedom spherical joints 126, 127. Aswith the FIG. 1 embodiment, a seventh degree of freedom is provided viaa rotary joint/actuator 128 integrated with the support member 112 forrotating a tool mount 114 relative to the support member.

A further embodiment that employs three degree of freedom parallel, asopposed to serial, actuators as the first and second actuators systemsis shown in FIG. 3. In FIG. 3, elements similar to those found in theFIGS. 1 and 2 embodiments are given corresponding reference numbers inthe 200s. Specifically, in the FIG. 3 embodiment, each of the first andsecond actuator systems 216, 218 comprises three linear joints/actuators238 arranged in parallel. Each of the linear joints/actuators 238 isconnected at one end to a solid mount 224 via a respective three degreeof rotary freedom spherical joint 239. The other end of the each of thelinear joint actuators 238 is connected to a fixed sphere 240 so as toform a tripod arrangement in which the tip, i.e. the fixed sphere, canbe moved in space. The fixed sphere is part of a spherical joint 226,227 that defines the attachment point to the support member 212. In thiscase, one of the three linear joint actuators 238 of each actuatorsystem 216, 218 is rigidly connected to the fixed sphere while the othertwo are connected to the sphere in such a way that they each can rotateabout the sphere with three degrees of freedom. Again, a seventh degreeof freedom is provided via a rotary joint/actuator 228 integrated withthe support member 212 for rotating a tool mount 214 relative to thesupport member 212.

As shown in FIGS. 4-5, the first and second actuator systems can havedifferent configurations. More specifically, in the embodiment of theinvention shown in FIG. 4, the first actuator system 316 comprises athree degree of freedom parallel linear actuator having a tripodconfiguration like that used for the first and second actuator systemsin the embodiment of FIG. 3. In FIG. 4, elements similar to those foundin the embodiments of FIGS. 1-3 are given corresponding referencenumbers in the 300s. In the FIG. 4 embodiment, the second actuatorsystem 318 comprises a three degree of freedom serial linear actuator(with linear actuators 320, 321, 322) like that used in the embodimentof FIG. 1. Again, each of the actuator systems 316, 318 connects to thesupport member 312 at a respective attachment point comprising aspherical joint 326, 327 and a rotary joint/actuator is integrated withthe support member 312 for rotating a tool mount 314 relative to thesupport member to provide the seventh degree of freedom.

In the embodiment of FIG. 5, elements similar to those found in theembodiments of FIGS. 1-4 are given corresponding reference numbers inthe 400s. In FIG. 5, the first actuator system 416 comprises a threedegree of freedom serial rotary actuator (with rotary actuators 430,431, 432) like that used in the embodiment of FIG. 2 and the secondactuator system 418 comprises a three degree of freedom parallel rotaryactuator, which is generally similar to the three degree of freedomparallel tripod actuators of FIG. 3 but with rotary joints/actuators 445instead of linear joints/actuators. In particular, the three degree offreedom parallel rotary second actuator system 418 includes three legseach of which is connected to a respective rotary joint/actuator 445.Each rotary joint/actuator 445 is connected to the solid mount 424 androtates about a respective one of the Cartesian coordinate axes, i.e. x,y and z. Again, each of the actuator systems 416, 418 connects to thesupport member 412 at a respective attachment point comprising aspherical joint 426, 427 and a rotary joint/actuator 428 is integratedwith the support member 412 for rotating a tool mount 414 relative tothe support member to provide the seventh degree of freedom.

As shown in the embodiment of FIG. 6, the individual first and secondactuator systems 516, 518 can have mixed architectures including bothlinear and rotary joints/actuators. In FIG. 6, elements similar to thosefound in the embodiments of FIGS. 1-5 are given corresponding referencenumbers in the 500s. In the FIG. 6 embodiment, the first actuator system516 is a serial arrangement that includes a z-axis rotary joint/actuator547 having an output shaft connected to a link that connects to a linearjoint/actuator 548 that, in turn, is connected to a y-axis rotaryjoint/actuator 549. The second actuator system 518 is a parallel tripodarrangement consisting of one leg with a rotary joint/actuator 551 andtwo legs with linear joints/actuators 552. Again, each of the actuatorsystems 516, 518 connects to the support member 512 at a respectiveattachment point comprising a spherical joint 526, 527 and a rotaryjoint/actuator 528 is integrated with the support member 512 to rotate atool mount 514 relative to the support member to provide the seventhdegree of freedom. The FIG. 6 embodiment illustrates that anycombination of rotary and linear actuators that provides the desiredthree degrees of freedom can be used to form the first and secondactuator systems.

A preferred hybrid serial/parallel manipulator arrangement isschematically illustrated in FIG. 7. In FIG. 7, elements similar tothose found in the embodiments of FIGS. 1-6 are given correspondingreference numbers in the 600s. In the FIG. 7 embodiment, each of thefirst and second actuator systems 616, 618 is a three degree of freedomserial arrangement using rotary joints/actuators. Referring specificallyto FIG. 7 of the drawings, each of the first and second actuator systems616, 618 includes a first rotary joint 654 that is connected to a solidmount 624. The output shaft of the first rotary joint 654 comprises afirst link 655 that connects to a second rotary joint 656. The secondrotary joint 656 has a rotational axis that extends perpendicular to therotational axis of the first rotary joint 654. The output of the secondrotary joint 656 comprises a second link 657 that defines one of theside legs of a four-bar mechanical linkage 660. The four-bar linkage 660of each of the actuator systems includes 2 side legs 657, 661 and upperand lower arms 662, 663. The four bars, i.e. the two side legs and theupper and lower arms 657, 661, 662, 663, of the 4-bar mechanical linkage660 are interconnected via rotary joints 664 each having one degree ofrotational freedom, e.g. pinned pivots. The rotational axes of the fourrotary joints 664 in the four-bar linkage 660 extend parallel to eachother and to the rotational axis of the second rotary joint 656.

The lower arm 663 of each of the four-bar linkages 660 connects to thesupport member 612 at a respective connection point. In this case, theupper connection point includes two rotary pivots 666, 667 havingrotational axes extending perpendicular to each other so as to providethe connection point with two rotational degrees of freedom and thelower connection point includes a spherical joint 627 with three degreesof rotational freedom. As with the embodiments of FIGS. 1-6, the firstand second actuator systems 616, 618 can provide a total of six degreesof freedom and a seventh degree of freedom is provided by a rotaryjoint/actuator 628 that is integrated with the support member 612 forrotating a tool mount 614 relative to the support member.

The arrangement of FIG. 7 is better understood with reference to FIG. 8,which illustrates a more specific embodiment of a manipulator having theconfiguration shown schematically in FIG. 7. In FIG. 8, elements similarto those found in the embodiments of FIGS. 1-7 are given correspondingreference numbers in the 700s. The embodiment of FIG. 8 includes aheader 724 serving as a solid mount that connects the first and secondactuator systems 716, 718 together. In particular, both the first andsecond actuator systems 716, 718 include a first rotary joint/actuator770 that includes a rotatable first link 755 that extends, in this case,downward from the header 724. In the illustrated embodiment, the firstlink 755 rotates about its longitudinal axis which extends perpendicularto the header 724. To this end, the first rotary joint/actuator 770 ofeach of the first and second actuator systems 716, 718 includes a rotarypivot 754. The first rotary joint/actuator 770 further includes amechanism for driving rotation of the respective first link 755 relativeto the header 724. In this instance, the rotating mechanism comprises agear drive that includes a motor 771 with a geared output shaft that ismounted on the header 724 and acts on a gear 772 supported on the firstlink 755.

The first link of each of the first and second actuator systems 716, 718connects to a second link 757 having, in this case an L-shapedconfiguration and which forms part of a four-bar mechanical linkage 760.The first link 755 connects to the second link 757 via a second rotaryjoint/actuator 774. The second rotary joint/actuator 774 includes afirst pinned pivot 756 that permits the second link 757 to rotaterelative to the first link 755 about an axis that extends perpendicularto the rotational axis of the first link 755. The second rotaryjoint/actuator 774 further includes a mechanism for rotating the secondlink 757 relative to the first link 755 that comprises a motor 775 witha geared output shaft that is mounted on the second link 757 and acts ona gear 776 supported on the first link 755.

The L-shaped second link includes an upper portion 778 that connects tothe first link 755 and a lower portion 779 that, as previously noted,forms part of a four-bar mechanical linkage 760. In the illustratedembodiment, the four-bar linkage 760 comprises the lower portion 779 ofthe second link 757 which defines one side leg of the linkage, a secondside leg 761 and upper and lower arms 762, 763. The second side leg 761extends parallel to the lower portion 779 of the second link 757 and isconnected thereto by the upper arm 762 and the lower arm 763. Morespecifically, the upper arm 762 is pivotally connected to the lowerportion 779 of the second link 757 and to the second side leg 761 byrespective pinned pivots 764. Similarly, the lower arm 763 is pivotallyconnected to the lower portion 779 of the second link 757 and the secondside leg 761 by respective pinned pivots 764. The rotational axes of thefour pinned pivots 764 in the four-bar mechanical linkage 760 extendparallel to each other and to the rotational axis of the pinned pivot756 connecting the first and second links 755, 757 and in a planeperpendicular to the plane containing the rotational axes of the rotarypivot 754 connecting the first link 755 and the header 724.

In the illustrated embodiment, the four-bar linkage 760 of each of thefirst and second actuator systems 716, 718 is driven by a third rotaryjoint/actuator 782 comprising the pinned pivot 764 between the lowerportion 779 of the second link 757 and the upper arm 762 and a geardrive that includes a motor 783 with a geared output shaft that ismounted on the lower portion 779 of the second link 757. The gearedoutput shaft of the motor 783 acts on a gear 784 mounted on the upperarm 762 so as to drive pivotal movement of the lower portion 779 of thesecond link 757 relative to the upper arm 762 and, in turn, movement ofthe entire four-bar linkage 760. While the drive for the four-barlinkage 760 could be arranged at any of the four pivots 764 of thelinkage, arranging the drive where shown in the embodiment of FIG. 8helps minimize the rotational inertia of the manipulator by keeping thevarious motors close to a central point. Thus, less torque is requiredfor each individual motor to move the other motors and/or hold them in aparticular position.

With the first and second actuator systems 716, 718, the third rotaryjoint/actuator 782, including the gear drive at the pinned pivot 764joining the upper arm 762 and the lower portion 779 of the second link757, generally controls the tilt of the lower arm 763. The second rotaryjoint/actuator 774, including the gear drive at the pinned pivot 756joining the first and second links 755, 757, generally controls the tiltof the entire lower portion of the respective actuator system includingthe position of the driven pinned pivot 764 of the four-bar linkage 760.Thus, to make the lower arm 763 move in a linear direction (i.e., in adirection coincident with its longitudinal axis) in the plane in whichit is illustrated in FIG. 8, the two gear drives of the second and thirdrotary joints/actuators 774, 782 must be controlled so that they worktogether in tandem. For example, to produce a linear movement of thelower arm 763, the gear drive of the second rotary joint/actuator 774can be used to pivot the second link 757 relative to the first link 755and thereby generally sweep the lower arm 763 back and forth while thegear drive of the third rotary joint/actuator 782 rotates the upper arm763 relative to the second link 757 in a direction counter to thatproduced at the pinned pivot 756 of the second rotary joint/actuator inorder to keep the lower arm 763 level. To move the lower arm 763 in alinear direction in a different plane than that illustrated in FIG. 8,requires the manipulation of the drive motors of all three of the rotaryjoints/actuators in the respective actuator system 716, 718.

The lower arm 763 of each of the first and second actuator systems 716,718 extends to a support member 712 to which it is connected. In theillustrated embodiment, the lower arm 763 of the first actuator system716 connects to the support member 712 via a rotary pivot 766 and apinned pivot 767 so as to provide two degrees of rotational freedom. Thelower arm 763 of the second actuator system 718, in turn, connects tothe support member 712 via a spherical joint 727 that provides threedegrees of rotational freedom. As noted above, limiting the one of theconnection points of the first and second actuator systems to a twodegree of freedom joint system such as with the first actuator system716 in the embodiment of FIG. 8 helps prevent free rotation of thesupport member 712, which can occur if two three degree of freedomspherical joints are used

In the illustrated embodiment, the support member 712 has an L-shapedconfiguration including a first longer leg to which the lower arms 763of the first and second actuator systems 716, 718 are connected and asecond shorter leg to which a tool mount 714 is connected. For rotatingthe tool mount 714 relative to the support member, a rotaryjoint/actuator 728 is integrated with the support member 712. The rotaryjoint/actuator 728 integrated with the support member 712 includes arotary pivot 786 that connects the tool mount 714 to the support member712. In this instance, the rotary pivot 786 has a rotational axis thatextends parallel to the rotational axis of the rotary pivots 754connecting the first links 755 of the first and second actuator systems716, 718 to the header 724. For driving rotation of the tool mount 714relative to the support member 712, the rotary joint/actuator 728includes a gear drive which includes a motor 787 with a geared outputshaft that acts on a gear 788 connected to the tool mount 714. Therotation of the tool support 712 produced via the gear drive and rotarypivot 786 is independent of any rotation of the tool support 712 thatmay be produced via the first and second three degree of freedomactuator systems 716, 718.

In the embodiment of FIG. 8, the load on which the first and secondactuator systems are acting includes the support member 712, the toolmount 714 and the tool mounted to the tool mount 714. To help minimizethe size of the motors that are required as well as the power that mustbe applied to maintain the manipulator in a given position, the firstand second actuator systems can be configured so as to helpcounterbalance this load. In particular, the individual actuator systemscan be arranged or configured such that with one or more of the rotaryjoints/actuators parts of the respective actuator system are arranged onthe side of the rotational axis defined by that rotary joints/actuatorsopposite the side on which the load or other parts of the actuatorsystem are arranged.

For example, with respect to the embodiment of FIG. 8, the four barmechanism is not required to achieve three degrees of freedom of each ofthe actuator systems. Instead, the gear drive of the third rotaryjoint/actuator 782 at the pinned pivot 764 between the lower portion 779of the second link 757 and the upper arm 762 could be relocated to thejoint 764 between the lower portion 779 and the lower arm 763, in whichcase the upper arm 762 and second side leg 761 could be eliminated.However, such an arrangement is not well balanced as the weight of thesupport member 712, tool support 714 and tool will create a moment thatwill pull downwards on the distal end of the lower arm 763. Because itis arranged on the opposite side of the rotational axis defined by thethird rotary joint/actuator, the four-bar linkage in the embodiment ofFIG. 8 provides a counterbalance to this moment, which reduces theoverall load on the gear drive. In a similar fashion, the actuatorsystems could be arranged such that some is arranged behind therotational axis defined by the first rotary joint/actuator 770 (such asthe case with the first actuator system 716) to provide a counterbalanceto the load (support member 712, tool mount 714 and tool) which isarranged in front of the axis.

In the embodiment shown in FIG. 8, each of the first and second actuatorsystems 716, 718 includes three rotary joint/actuators 770, 774, 782(i.e. rotary joint and gear drive combinations) and thus can move theend point of its respective lower arm 763 with three degrees of freedom.Thus, the first and second actuators systems 716, 718 provide a total ofsix degrees of freedom. The rotary joint/actuator 728 integrated withthe support member 712 provides a seventh degree of freedom. While themanipulator has seven degrees of freedom, one degree of freedom is maderedundant by the structure of the manipulator including the fixed lengthof the support member 712. Thus, the resulting seven degree of freedommanipulator provides coordinated motion of the tool mount 714 in sixdegree of freedom space. While gear drives are shown for each of therotary joints/actuators in the embodiment of FIG. 8, other drive systemsalso can be used. For example, another preferred drive system forproducing rotation at the respective rotary joints is a friction cableor chain drive. Other friction drives such as a belt drive could also beused. The reduction ratios produced by the drive systems can range from1:1 to 10,000:1.

As will be appreciated by those skilled in the art, six degrees offreedom are all that is required to define the position of the toolmount in space. Thus, the seventh degree of freedom provided by theexemplary manipulators shown in FIGS. 1-8 is a redundant degree offreedom. The redundant seventh degree of freedom provides for goodtorque delivery in a wider variety of orientations as compared to amanipulator having just six degrees of freedom (i.e., no redundantdegrees of freedom) and expands the operational envelope beyond whatmany six degree of freedom manipulators can achieve. The range of motionof all hybrid serial/parallel mechanisms is defined by a series ofsingularity points where the manipulator becomes locked and can nolonger move freely. At these singularity points, the manipulator becomeslocked and can no longer move freely. These singularity points happenwhen the manipulator is at full extension with the mechanical elementsof the manipulator binding against one another in such a way that themanipulator cannot provide enough force or torque to move itself andwhatever tool is being manipulated.

For example, if the upper first actuator system 716 of the manipulatorof FIG. 8 were limited to a two degree of freedom actuator system, theredundant degree of freedom would be eliminated and the degrees offreedom of the actuator systems would match up with the degrees offreedom available at the attachment point joints 726, 727. With therotary joint/actuator 728 carried by the support member 712, themanipulator would have a total of six degrees of freedom. However, theability of such a manipulator to create torque on the support member 712is reduced as the line connecting the attachment points of the first andsecond actuator systems to the support member changes from a vertical toa more horizontal orientation. Specifically, the ability to createtorque is reduced by the sine of the angle that the line connecting thetwo attachment points forms with a horizontal plane. As that angle, andthe sine of that angle, approaches zero, the lever arm that could beused to create torque in the support arm approaches zero length. In sucha situation, force can only be applied to the support member in theaxial direction relative to the line connecting the attachment points.This restricts the work that can be done by the manipulator.

Adding a third degree of freedom to the first actuator system 716 helpsalleviate this problem. In particular, the additional degree of freedomallows a force to be produced in a direction perpendicular, or at someother angle, relative to the line connecting the attachment points 726,727. Thus, torque can be produced in any orientation of the supportmember 712.

For sensing the positions of the various rotary joints 754, 756, 764 onthe manipulator and, in turn, the support member 712 and tool mount 714all or some of the rotary joints can be equipped with position sensors.Each of the drive systems of the manipulator can be in communicationwith the controller and the position sensors can provide positioninformation in a feedback loop to the controller. It will be appreciatedthat any number of different conventional position sensors can be usedsuch as, for example, optical encoders. Moreover, the various drivesystems can also be equipped with force sensors for sensing the forcesor torques applied by the actuators so as to enable a determination ofthe forces and torques applied to the support member and/or the toolmount. This information can again be provided in a feedback control loopto the controller, for example to allow force feedback to the inputdevice of a haptic interface. Of course, any known method for measuringforces and/or torques can be used, including, for example, foil type orsemiconductor strain gauges or load cells.

Special control techniques are necessary when two or more of the drivesystems of the joints/actuators 770, 774, 782 of the first and secondactuator systems 716, 718 are coupled together in parallel throughredundant application to drive the mechanism. In such situations, two ormore drive systems may be supplying power to the same elements of themanipulator mechanism to accomplish the same movement. These situationsoccur because of the seventh redundant degree of freedom. The specialcontrol techniques that are necessary include methods to control torqueand position when multiple drive systems, for example two drive systems,are supplying torque to an element of the manipulator at the same time.These methods can include sharing the load between the two drive systemsaccording to a complex Jacobian transform relating the load in Cartesianspace to joint torque. Alternatively, the load can be dividedproportionally with one drive system serving as the position controlmaster and with the other drive system serving as a force applying slaveelement. One of the redundant drive systems also could be allowed torest so that its movement does not conflict with movement of the otherdrive system involved in moving the particular element of themanipulator mechanism. The most complex interactions between the variousdrive systems occur when the support member 712 and tool mount 714 areat an angle to the horizontal and the centerline of the manipulatormechanism planes. In this particular condition, all of the drive systemsare interacting with one another. The Jacobian transform method is thepreferred method for handling those complex interactions.

In view of the foregoing, it will be appreciated that the presentinvention provides a manipulator that provides seven degrees of freedom.The redundant seventh degree of freedom provides improved performance byimproving torque delivery certain orientations and by helping toeliminate certain singularity points. Manipulators having first andsecond actuator systems with particular configurations are shown in thedrawings and described herein. Of course, other types of three degree offreedom actuator systems could also be used. For example, each of thefirst and second actuator systems could be based on a so-called r-thetamechanism, which is a two degree of freedom radial coordinate engine. Afurther actuator can then be connected to each r-theta mechanism whichis able to independently move the corresponding r-theta mechanism out ofits respective rotational plane. The result is that the first and secondactuator systems are two independent three degree of freedom actuatorsystems. Other arrangements are also possible.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A manipulator comprising: a body; a first actuator system connectedto the body at a first attachment point and capable of moving the firstattachment point with at least three degrees of freedom; a secondactuator system connected to the body at a second attachment point andcapable of moving the second attachment point with at least threedegrees of freedom; and a third actuator system integrated with the bodyand capable of moving at least a portion of the body with at least onedegree of freedom.
 2. The manipulator of claim 1 wherein the firstattachment point comprises a three degree of freedom joint.
 3. Themanipulator of claim 1 wherein the first attachment point comprises atwo degree of freedom joint.
 4. The manipulator of claim 1 wherein thefirst attachment point comprises a two degree of freedom joint and thesecond attachment point comprises a three degree of freedom joint. 5.The manipulator of claim 1 wherein the third actuator system is a rotaryactuator supported on the body for rotating at least a portion of thebody about a rotary axis.
 6. The manipulator of claim 1 wherein each ofthe first and second actuator systems comprises a serial actuatorsystem.
 7. The manipulator of claim 6 wherein each of the first andsecond actuator systems employs at least three linear joints/actuators.8. The manipulator of claim 6 wherein each of the first and secondactuator systems employs at least three rotary joints/actuators.
 9. Themanipulator of claim 6 wherein at least one of the first and secondactuator systems employs a combination of rotary and linearjoints/actuators.
 10. The manipulator of claim 1 wherein both the firstand second actuator systems comprise serial actuator systems.
 11. Themanipulator of claim 10 wherein each of the first and second actuatorsystems employs at least three linear joints/actuators.
 12. Themanipulator of claim 10 wherein each of the first and second actuatorsystems employs at least three rotary joints/actuators.
 13. Themanipulator of claim 10 wherein at least one of the first and secondactuator systems employs a combination of rotary and linearjoints/actuators.
 14. The manipulator of claim 1 wherein the firstactuator system comprises a serial actuator system and the secondactuator system comprises a parallel actuator system.
 15. Themanipulator of claim 10 wherein the first and second actuator systemseach include a plurality of rotary joint/actuators.
 16. The manipulatorof claim 10 wherein the first and second actuator systems each includefirst and second rotary joints/actuators arranged in series.
 17. Themanipulator of claim 16 wherein the first and second actuator systemseach include a four-bar linkage arranged in series with the two rotaryjoints/actuators.
 18. The manipulator of claim 17 wherein one corner ofthe four-bar linkage comprises a third rotary joint/actuator for drivingmotion of the four-bar linkage.
 19. The manipulator of claim 18 whereinthe corner of the four-bar linkage comprising the third rotary jointactuator is the corner closest to the first and second rotaryjoints/actuators so as to minimize the rotational inertia of therespective actuator system.
 20. The manipulator of claim 17 wherein thefour-bar linkage includes an arm that connects to the support member atthe respective attachment point.
 21. The manipulator of claim 21 whereinthird rotary joint actuator defines a third rotary axis and wherein aportion of the four bar linkage is arranged on a first side of the thirdrotary axis to help counterbalance the body and another portion of therespective actuator system that are arranged on an opposing second sideof the third rotary axis.
 22. The manipulator of claim 16 wherein one ofthe plurality of rotary joints/actuators defines a first rotary axis andwherein the first and second actuator systems are configured such that aportion of the respective actuator system is arranged on a first side ofthe rotary axis to help counterbalance the body and another portion ofthe actuator system that is arranged on an opposing second side of therotary axis.
 23. The manipulator of claim 16 wherein the plurality ofrotary joints/actuators are driven via respective gear drives.
 24. Themanipulator of claim 16 wherein the plurality of rotary joints/actuatorsare driven via respective cable drives.
 25. The manipulator of claim 16wherein the plurality of rotary joints/actuators are driven viarespective chain drives.
 26. The manipulator of claim 16 wherein theplurality of rotary joints/actuators are driven via respective frictiondrives.
 27. The manipulator of claim 25 wherein the friction drives arebelt drives.
 28. The manipulator of claim 25 wherein the friction driveis a cable drive.
 29. The manipulator of claim 1 wherein the bodyincludes a tool mount and the tool mount comprises the portion of thebody moved by the third actuator system.